1. Field of the Invention
The present invention generally relates to electronic devices including mobile devices, and more particularly, to wireless charger and devices for wireless energy transfer, for example, to an electronic device.
2. Description of the Related Art
Systems for transfer of electromagnetic energy may be classified into radiating and non-radiating systems. Radiating systems for transfer of energy are based on narrow-band transmitters and use electromagnetic radiation in a far-field region. Non-radiating systems for a transfer of energy are based as a rule on electromagnetic induction and use an evanescent field in a near-field region.
The resonance inductive method of a wireless transfer of energy is based on a following principle: inductance coils with identical own resonance frequencies form the resonance system interchanging energy through a magnetic field.
An electronic device, charged by a wireless method, contains a built-in receiving coil which is sometimes called the energy receiver. The electronic device is charged at allocation over the transmitting coil of a wireless charger which is sometimes called the energy transmitter. The induced electromotive force is created in the receiving coil due to the magnet field generated by the transmitting coil. The effective transfer of energy to one or several electronic devices simultaneously causes the necessity of increasing of the dimension of the transmitting coil or use of a large number of transmitting coils. The increasing of the dimension of the transmitting coils increases the level of spurious electromagnetic radiation and complicates providing of uniform efficiency of a transfer of energy by a surface of a charger. This causes difficulty in the application of prior-art wireless technologies of transfer of the electric power for charging of electronic devices such as mobile devices and other household appliances.